Non-Contact Sensor for Oxide Data Disks
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Oxide data disks contain many thin layers of different materials. For example, a current disk has (counting out from the aluminum alloy substrate) (1) a sealing coating, (2) magnetic coating to sealing coating interface, (3) bulk magnetic coating, (4) buffed coating to air interface, and (5) lubricant. Each of these interfaces contains charge layers corresponding to the respective work functions of the materials and their state of mechanical/electrical stress. It has been determined that the interfacial (and perhaps bulk) charges at every disk-making process can be detected, and their uniformity is a clear indicator of the oxide uniformity of the final finished disk. The charges on the disk can be detected by the non-contact charge probe shown in the figure. Typical component values are shown.